As described in Japanese unexamined patent application publication No. 2005-70402, an image-forming device known in the art that employs an electrophotographic system has a developing cartridge that is detachably mounted in a device body for supplying developer to a photosensitive drum.
One such developing cartridge that has been proposed is a developing unit comprising a developing roller that carries toner, a supply roller that supplies toner to the developing roller, a first contact member that electrically connects to a rotational shaft of the developing roller, and a second contact member that electrically connects to a rotational shaft of the supply roller.